Hello my name is Kaitlin and I am in fifth grade. I just recently had a test on multiplying decimals and I did not do really well on it. Only 5 kids out of 19 got a passing grade. My teacher says that she will give us a different test and we can take it again, but I'm still not sure of it. My teacher has taught me a lot and she had done a wonderful job of it but I'm just confused with where to put the decimals and stuff like that. I have a math practice workbook that I do for fun and they have nothing on decimals in it. I have checked on websites to try to find worksheets but I really couldn't find a good one. Can you please help me either give me some tips or clues or send me a worksheet. I'm a good student and I do not want to do bad on the test next time. Even if you do not get this by the time I take the test I would still like to know how to do it for the up com! in! g years. Thank you very much. Sincerely,
Suppose that you have to multiply 2.13 by 5.1. I would get
2.13 5.1 ----- 213 1065 ---- 10863Now count the digits to the right of the decimal in the two numbers you multiplied. In 2.13 there are 2 digits to the right of the decimal and in 5.1 there is 1 digit to the right of the decimal. Thus in the two numbers you multiplied there is a total of 3 digits to the right of the decimals. Thus, in the answer you need a 3 digits to the right of the decimal. Hence the answer is 10.836.
You can also use an aproximation to determine where the decimal should go. 2.13 is a little more than 2 and 5.1 is a little more than 5 so 2.13 x 5.1 is a little more than 2 x 5 which is 10. Thus when you multiply and get 10863 you know that the decimal should go between the 0 and the 8.
Lets do another, 22.53 x 13.41
This time I'll do the approximation first. 22.53 x 13.41 is approximately 20 x 13 = 260.
22.53 13.41 ------ 2253 9012 6759 2253 -------- 3021273
Using the approximation method the answer is 302.1273. Certainly 30.21273 is too small and 3021.273 is too large. Using the counting technique, there are 2 digits to the right of the decimal in 22.53 and 2 digits to the right of the decimal in 13.41, thus there should be 2 + 2 = 4 digits to the right of the decimal in the answer. Hence the answer is 302.1273I hope this helps,