Estimating Sums & Differences Worksheets - Math Worksheets 4 Kids Estimate the sums and differences in these printable worksheets, designed for grade 3, grade 4, and grade 5 children, by rounding each number to the nearest ten, hundred, thousand or hundred thousand. Front-end estimation method may also be used to estimate the value in some of the pdf worksheets. Grab hold of a few of these handouts for free!