SonshineLearner Posted November 16, 2009 Share Posted November 16, 2009 Hi There, So, I have 5a, 5B and 6A along with the HI Guide. I'd love to understand the the Estimate Rules that they use. For example: 959 / 33 ~ 900 / 30 = 30 So, I think that the / is for divide, right?? Anyway, that's what I mean in the above problem. Now,If I were just rounding, I'd go up to 1000 because the "59" would be enough to get it up to 1000. and I can see the 33 becoming 30. Could you refresh me or teach me why it's like this?? Thanks! Carrie Quote Link to comment Share on other sites More sharing options...
TrixieB Posted November 16, 2009 Share Posted November 16, 2009 It has been a while since we covered this (last year) but I think they were trying to get the child to see that 30x30=900. There isn't such a nice round estimate for 30x?=1000, so I think that is why they used 900 instead. Quote Link to comment Share on other sites More sharing options...
Matryoshka Posted November 16, 2009 Share Posted November 16, 2009 The point of estimating in a case like this is to make the math easy enough to do in your head, and get an answer that gives you a reasonable ballpark of what the exact answer would be, so if you did the exact math you could compare it to the estimate to see if it makes sense. In this case, 900 is easily divisible by 30. 1000 would not be, so that would be a silly thing to round to. You want to round the number you're dividing to the nearest even mulitiple of the divisor. So, your choices are not, which is nearer, 900 or 1000, but which is nearer, 900 or 1200, which are the two nearest multiples of 30. It's nearer to 900, so you go with that. For another example, if you're estimating 2345 / 93 ... the 93 rounds to 90. The multiples you'd want to choose between would be mutiples of 90 - 1800 or 2700. 2345 is closer to 2700, so your estimate would be 2700 / 90, and your estimated answer would be 30. Quote Link to comment Share on other sites More sharing options...
SonshineLearner Posted November 16, 2009 Author Share Posted November 16, 2009 Ok:-) Got it:-) I think..... I really intend to start my son (6) on Singapore within the next few months. I need to find a used set. He already thinks like this..... and so I know that he'll do great with it. Math is his strong subject. I hope to bridge the gaps of Singapore in my head...between my two kiddos:-) Thanks! Carrie Quote Link to comment Share on other sites More sharing options...
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