Subtract 3-Digit − 2-Digit Mentally

Step 1 of 4 · The trick

Subtracting 27 is awkward · subtracting 30 is easy!

Round up the small number to the next 10.
Subtract that easy number first.
Then add back the extra you took.

134 − 27 → 134 − 30 = 104 → 104 + 3 = 107

Step 2 of 4 · 134 − 27

134 − 27 = ?

Round 27 → 30 (extra 3)

134 − 30 = 104

104 + 3 = 107

134 − 27 = 107

Step 3 of 4 · 245 − 19

245 − 19 = ?

Round 19 → 20 (extra 1)

245 − 20 = 225

225 + 1 = 226

245 − 19 = 226

Step 4 of 4 · Your turn

Round up · subtract · add back.

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Nice work!

You used the round-and-adjust trick.