Second Grade · Math · week 13

Subtracting tens and ones (no regrouping)

Subtract 2-digit numbers by subtracting ones from ones and tens from tens, when no regrouping is needed.

Subtracting works like adding: line up ones under ones and tens under tens, then subtract each column separately. As long as the top ones digit is bigger than the bottom ones digit, you never need to regroup.

Always subtract ones first, then tens. Say each step out loud so you do not lose your place.

📋 For the teacher
Teach it (10–15 min):
  • Line up digits by place carefully, just like with addition -- a crooked line-up causes most mistakes.
  • Check before starting: is the top ones digit bigger than or equal to the bottom ones digit? If yes, no regrouping is needed (that comes next week).
  • Have them check their answer by adding it back to the number subtracted -- it should rebuild the original number.
  • Use blocks to show the "take away" action physically if the written steps feel shaky.
Talk about it:
  • Why do we subtract the ones column before the tens column?
  • How can adding your answer back check a subtraction problem?
  • What tells you a subtraction problem will NOT need regrouping?

Mastery looks like: They subtract two 2-digit numbers without regrouping accurately and check their work by adding back.

Common stumbles: Subtracting the top digit from the bottom digit instead of the reverse; misaligning place value columns.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →SubtractionTake away and count back, step by step.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
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