Line up hundreds, tens and ones. Start with the ones. Regroup when a column adds to 10 or more, or when the top digit is smaller than the one below it.
regrouptrade 10 ones for a ten, or a ten for 10 ones
sumthe answer to +
differencethe answer to −
place valuewhat a digit is worth from where it sits
Watch for: Taking the smaller digit from the bigger one in every column instead of regrouping. Forgetting the ten or hundred carried over. Digits drifting out of their columns.
At home: Check a subtraction by adding: if 884 − 751 = 133, then 133 + 751 should make 884.
Sample sheet and answer key
Luna's Space Adventure
Grade 3 · Adding and subtracting within 1000 · 3.NBT.A.2
NameDate
Astronaut Luna is exploring a far-off corner of space. Solve each problem to help Luna's mission go smoothly!
Adding
1
341+340
2
535+282
3
290+489
4
259+111
5
586+207
Subtracting
1
976−661
2
739−323
3
365−120
4
912−552
5
817−383
Riddle time
Solve each one, then use the code to answer the riddle.
New problems every time, three levels (gentle, core and stretch), themes to pick from, a second page if you want one. Each sheet comes with an answer key and a one-page guide for grown-ups.
