Two-Digit Subtraction Without Regrouping

We start with the easy subtraction case — when each digit in the bottom number is smaller than the digit above it.

What we're learning

That two-digit subtraction is just subtraction in each place column
The vertical "stacked" form for subtraction
Why we still subtract the ones first

The easy case first

78 − 35 is the easy case. Why? Because in each column, the top digit is bigger than the bottom digit:

Ones: 8 is bigger than 5. We can do 8 − 5 = 3.
Tens: 7 is bigger than 3. We can do 7 − 3 = 4.

   7  8
 − 3  5
 ------
   4  3

Answer: 43.

This is the comfortable case. Build it solid before moving to regrouping in the next lesson.

Subtract the ones first

Same as addition: we always start with the ones place. In the easy case it doesn't seem to matter — you'd get the same answer subtracting tens first. In the next lesson (regrouping) it absolutely matters. Build the habit now.

Try it together

Use a notebook with a place-value column drawn in:

| Tens | Ones |
|  7   |  8   |
|  3   |  5   |
| ---  | ---  |
|  4   |  3   |

Try these together. Each one is regrouping-free:

47 − 23
89 − 36
65 − 14
90 − 60
58 − 35

The fourth one is interesting: 90 − 60. The ones are both 0; 0 − 0 = 0. The tens are 9 − 6 = 3. Answer: 30.

Connecting back to addition

Notice: subtraction is the inverse of addition. If 35 + 43 = 78, then 78 − 35 = 43. Same three numbers; just rearranged.

Have your child check their subtraction answers by adding the answer back to the bottom number. They should get the top number. This is the most useful self-checking habit in elementary math.

  78          43          43
− 35    →   + 35    →   + 35
  --          --          --
  43          78          78  ✓

Watch for

Subtracting the smaller from the bigger by reflex. A child who hasn't internalized that order matters will look at 47 − 23 and read the ones column as "3 − 7" but answer 4 (because 7 − 3 = 4). The right answer for the ones is 7 − 3 = 4 here, but only because we read top-minus-bottom. When the digits are 3 on top and 7 on bottom, subtraction needs regrouping (next lesson). Get the order right now.
Skipping the column lineup. Same as addition — 78 − 5 requires lining up the 5 under the 8. Don't let it drift left.
Confusing minus and equals signs. − and = look similar to a 6-year-old. Have them write each one with a tiny gap above and below − and a wider gap for =.

Where this is going

Next lesson: regrouping — what to do when the ones digit on top is smaller than the ones digit below. This is the hardest concept in K-2 math and where everything we've built about place value pays off most.