# How long for a 10yob to do multi digit multiplication??

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How long "should" it take to do 16 multiplication problems that are double or triple digit on top and double on the bottom? (this is for a boy about to turn 10 years old)

My ds is taking waaaaaayyyyyy too long. He's thinking I'm giving too much, I know I'm not. He knows how to do them, I've watched. He can get thru it on his own. He does know his facts, now he's not speedy which is something we are working on separately but if he doesn't remember he can figure it out. He is sooo spacy but not with all things, mainly with this. I've even told him to take a breaks but ug..... We even did push ups today after every 10 min (after a long time of just sitting there) and he pushed thru it ... but his grades are really bad. This is a heart issue but I thought I'd start with confirmation on how long others his age take to do this work.

TIA,

Kathie in VA

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16 problems as you've described sound like a lot of brain drain for a 10 yob.

6-8 multiplications, plus 4 additions.... per problem.

16x6 = 96 multiplication facts

Keeping the digits aligned....

well, I'd probably have my kid do 2 sessions of 8, rather than one, long, session. But we do Singapore Math and not Saxon.....

K

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We don't do Saxon either. I'm using Mastering Math. So you think I should split the page in half? I can have him do 1/2 per session. Is 30-45 min way to short then?

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I'd say it depends on how long he's been working at the new skill. Has he mastered it? Or are you just starting to work through it?

I have found that there is an almost physical and visual rhythm to this algorithm -- starting with the ones, multiplying by the ones, tens, hundreds...back down to the tens, multiply by the ones, tens, hundreds...etc. And then, all that keeping things in columns and writing those tiny little numbers when you carry! It's a LOT.

I think it takes a lot of practice for that 'rhythm' to fall into place. Something I have found helpful: let him practice with numbers that are easier for a while.

For example, 521 X 25 is probably easier than 763 X 97 -- because most kids find multiplying by 2s, 5s, and 1s pretty easy. If he's still working on mastering those 6s and 9s, for example, keep the 6s and 9s out while he's learning the process. Now and then I'll even throw in a problem like 111 X 22, just for a breather. (We all need breathers now and then...)

Make some practice sheets with easy multiples for a week or so. He'll start to feel the 'rhythm' and it'll be easier to go on to harder problems. Tell him you've done this, and I bet he'll feel supported and encouraged and able to get to work.

Most students I've done this with seem to have a new energy about the work and I see improvement right away.

Good luck! I hope this helps.

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Have you tried lattice multiplication? We just found it, it's incredible, way easier, works, and now dh and I both use it (rather than regrouping).

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Perhaps it is me. He learned this at the end of last year. We pick it back up slowly, reviewing it all. We did it again with multiple colors (I like the bottom number to have a different color per digit. Then we use that color for that mulitplication. Then a different color yet for the final sum.) He did several of these and then said he didn't need the colors and then later said he didn't need the lines. ...

He also spends time each day with simple math facts... just to trying to memorize them faster.

Okay, perhaps I'll have him do 4 problems then check them with a calc and correct any errors. 4 more problems and then a break.

I just thought that somehow 16 of these problems was much less than what others his age were doing. I guess I'm wrong????

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Thanks for the suggestions but I'd really like to get some time estimates.

Anyone have a 9 or 10 year old boy that knows how to do multi-digit multiplication?

About how long does he take per problem?

About how many problems do you assign at a shot?

TIA

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How long "should" it take to do 16 multiplication problems that are double or triple digit on top and double on the bottom? (this is for a boy about to turn 10 years old)

For multiplication, if he understands the place value concept it will be easier to pick up. Something like this will take longer at first. When my 9yo daughter first learned this I made her check her work and it did take about 5 minutes per problem. Now she does them more quickly. I'd be patient with him, and make sure he gets what is going on before I'd be concerned about speed.

Good Luck :)

Edited by fractalgal
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Anyone have a 9 or 10 year old boy that knows how to do multi-digit multiplication?

Yes. If he's motivated and concentrating (usually because he has fewer problems to do and "the end is in sight") he can do 4 of these in 10 minutes. I show him a page of 6-8 of these types of problems (Singapore) and tell him that, if he gets the first two and the last two correct, he can skip the middle two problems. I've noticed this *greatly* improves his concentration. He hardly *ever* has those careless errors in that situation. If I gave him a page of 16 of those problems, I have no doubt it would take him an hour (at least). Then, add in more time off-task (because he feels overwhelmed and lets his mind wander) and all the stress he's feeling (and all the extra stress *I'm* feeling) and me nagging him... It's not worth it. I'd rather see that he knows how to do the math and is capable of doing it without the errors. I don't need the quantity, just the quality. But, like a pp said, we're using Singapore Math at home and it's a different approach.

Edited to add that this skill is review for my son, so it takes him less time than it used to. When he first learned this type of multiplication it took longer. He would often get confused about where to write certain numbers in the answers. We didn't use different colors, though. Sounds like a great idea! (I'm stashing it away for future use.)

Edited by zaichiki
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Don't know about the time, but turn the paper to "landscape" direction.... instead of "portrait".

Carrie:-)

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I've seen 9-11 year old students taking 10 - 20 minutes to get through 5 problems, especially if they are weak on their facts and have to count up or down (which makes them even more tired).

I won't let a student do more than that because they are exhausting when they are learning the process (and counting up and down because they aren't always solid on their facts).

I would rather a student do 3 per day for 2 months and get them right then to get 16 in one sitting.

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I agree with the estimates of 4-5 minutes per problem. Sixteen problems like that would take my son well over an hour. For a 10 yo that's a LOT to keep straight in his head, and it can be exhausting. I'd try giving him half as many problems and see if his speed and accuracy improve.

Jackie

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Thanks for the suggestions but I'd really like to get some time estimates.

Anyone have a 9 or 10 year old boy that knows how to do multi-digit multiplication?

About how long does he take per problem?

About how many problems do you assign at a shot?

TIA

I have a 10-year-old boy. Sixteen problem as you describe would take over an hour and it would be a very unpleasant experience for all. For a boy this age, I would break up the work into smaller chunks -- perhaps four or five, a break, another four or five. Doing 16 is a lot for a little guy that age. Eight problems per day would be more reasonable, imho.

I know my own son, who is a good student, wouldn't tolerate 16 complicated multiplication problems in one fell swoop. He's not being a jerk. That's just where he is developmentally.

Edited by tdeveson
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My 4th grade boy does 6 - 8 problems in about 15 minutes, but this is after gradually building up to that.

Back in August, it took more like 30 minutes, with lots of errors.

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My dd is 11. We are working on 3-digit multiplication. That many problems would make her shut down.

Graph paper and fewer problems has worked great and cut down on the number of minor mistakes.

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This type of problem was one of the few hang-ups (including tears) my youngest has had in math. There were just so many steps that she tired out very quickly. She was used to doing so much in her head and I think all the writing out was hard for her, too.

We suspended our regular math lessons for two weeks and I put 3 problems on the whiteboard each day and stood by her to make sure she did them quickly, maybe a minute or two each? I know that it helped to have the space as she is a messy writer and that was a frustration, too. The lined paper turned sideways did not help nearly as much as writing big on the whiteboard. I did have her say out loud what she was doing for the first of the three math problems.

After the two weeks, we went back to the math lessons and she seemed to take them in stride after that.

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my son struggles with multi-digit multiplication too. The main thing that helps him is doing it on graph paper. He is in 5th grade, almost 11. I am using Abeka, and while they have alot more available for practice, I only have him do 2. He would freeze when he saw even a row of 6 multi-digit problems. So we discussed and agreed on 2. He is not a slacker, and works very hard in all other areas. But his handwriting is still big for his age, and it was very difficult for him to line it all up. We are increasing the number required as his ability increase.

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My dd11 is finally getting her multiplication facts down (this is year *4* of working on them). One thing that has helped is assigning her all the odd problems. If she gets them all right (or misses only 1) then she doesn't have to do the others. It is a motivator... even if she knows how to do something, she was rushing and making silly mistakes. Since she hates math so much, knowing that if she concentrates and does her best she can skip half the work is a great motivator. She's now making 100%'s on her math, which she has never, never done.

The multi-digit multiplication still isn't quick, but it's not taking us an hour... maybe 20-25 minutes to do 6-8 problems.

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Thanks for the suggestions but I'd really like to get some time estimates.

Anyone have a 9 or 10 year old boy that knows how to do multi-digit multiplication?

About how long does he take per problem?

About how many problems do you assign at a shot?

TIA

Drew's 8, but...

multiplying by regrouping it takes about two to three minutes if he's on his game... if it's an 'I'm tired' day then it could take about five to eight.

multiplying by lattice it takes about the same on a good day, on an 'I'm tired' day it doesn't go too much longer, maybe as much as five, but never as long as regrouping. He enjoys the lattice method, though, and that makes all the difference.

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My dd is 11. We are working on 3-digit multiplication. That many problems would make her shut down.

*I* would run out of the room if someone gave me a page full of triple digit multiplication. After I fed it to them. :tongue_smilie:

Kathie -> My daughter is 12 and still takes quite a while to work through big multiplication problems. The development of the skill itself is much more important than the speed at which the calculations can be done. Y'know? :)

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