Adding or taking 10 changes the tens digit by one; adding or taking 100 changes the hundreds digit. The ones stay the same. Past 9 tens, the hundreds change too.
tens digitthe middle digit in a three-digit number
hundreds digitthe first digit in a three-digit number
in your headwithout writing it out
10 morethe number you get by adding 10
Watch for: Changing the ones digit: 824 + 10 = 825. Changing the tens when adding 100: 824 + 100 = 834. Forgetting the hundreds when the tens are 9: 495 + 10 is 505, not 405.
At home: Call out a number like 350 and take turns saying 10 more, 10 less, 100 more and 100 less.
Sample sheet and answer key
Freddie's Frog Pond
Grade 2 · Adding and subtracting 10 or 100 · 2.NBT.B.8
NameDate
Freddie the frog lives in a busy pond full of bugs, lily pads and friends. Solve each problem to help Freddie out!
Number machines
10 more or less changes the tens. 100 more or less changes the hundreds.
A chart that keeps going past 100. Down a row is still 10 more.
Answer key
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.
