84
−
29
Tip: Find the next ten of the second number (e.g., 29 → 30). Do M − 30 first, then add 30 − 29.
9 is near to 10. If the second number ends with 9, try subtracting the next ten first, then add the extra.
84
−
29
=
+
=
84
−
29
=
STEP 1
Subtract the tens from the first number.
84
−
=
STEP 2
Add the extra.
−
29
=
+
=