Estimating sums by rounding in your head worksheets

What is on this worksheet

Sums of two three-digit numbers with no boxes for the rounded numbers, so the child rounds to the nearest 100 mentally and writes only the estimate.

• Show a box for each rounded number: Off

You can change any of these settings above. Press "New problems" for a fresh set with the same settings, or pick Version A to Z to print different sheets for neighboring desks. The answer key always matches.

About estimating sums and differences worksheets

Each problem is a sum or a difference. Students round both numbers to the chosen place, then add or subtract the rounded numbers to get an estimate. By default there is a box for each rounded number, which keeps the steps visible; turn the boxes off to practice doing the rounding in your head.

Choose addition, subtraction or a mix, the place to round to, and how many extra digits make the numbers longer. Numbers that are exactly halfway are never used, and differences are always positive. Every sheet has a solved example and an answer key, and there is a large-print version.

Printing

US Letter or A4, portrait: choose your paper size above. Print at 100 percent (actual size). Use "Black and white" for the copier, or "Color" for display pages and mini books.