Line up tens and ones and start with the ones. When ones add to 10 or more, carry a ten. When the top ones digit is too small, trade a ten for 10 ones.
tens and oneswhat each digit in a two-digit number is worth
regrouptrade 10 ones for a ten, or a ten for 10 ones
sumthe answer to +
differencethe answer to −
Watch for: Taking the smaller ones digit from the bigger one: 82 − 53 = 31. Forgetting to add the carried ten. Crossing out a ten but not taking it away from the tens.
At home: Check a subtraction by adding back: if 82 − 53 = 29, then 29 + 53 should make 82.
Sample sheet and answer key
Freddie's Frog Pond
Grade 2 · Adding and subtracting within 100 · 2.NBT.B.5
NameDate
Freddie the frog lives in a busy pond full of bugs, lily pads and friends. Solve each problem to help Freddie out!
Adding
Add the ones first. Carry a ten when you need to.
1
35+31
2
13+80
3
68+14
4
43+54
5
57+34
Subtracting
Not enough ones? Trade a ten for ten ones.
1
52−23
2
43−19
3
71−24
4
48−36
5
60−25
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.
