Introduction to Subtraction

A. 1 ✓

When you subtract 1 from 2, you're left with 1. Think of it as: if you have 2 apples and take away 1, you have 1 apple left.

Why the others are wrong:
- B (2): This would be the answer if you didn't subtract anything.
- C (3): This is what you'd get if you *added* instead of subtracted.
- D (4): This doesn't match any basic operation on 2 and 1.

A. 3 is correct — You start with 5 pencils and give away 2, so 5 − 2 = 3 pencils remaining.

B. 4 is wrong — This might happen if you only gave away 1 pencil instead of 2.

C. 5 is wrong — This would be your starting amount, but you gave some away, so the total decreased.

D. 1 is wrong — This would only be correct if you gave away 4 pencils, not 2.

A. 5 ✓

When you subtract 4 from 9, you're left with 5. You can count it: 9, 8, 7, 6, 5 (that's four steps backward).

Why the others are wrong:
- B (3): That's 9 - 6, not 9 - 4
- C (7): That's 9 - 2, not 9 - 4
- D (6): That's 9 - 3, not 9 - 4

A. 0 is correct because when you subtract a number from itself, you always get zero. You're taking away the entire amount, leaving nothing.

B, C, and D are wrong because:
- B (1): This would only work if you subtracted 9 from 10
- C (2): This would only work if you subtracted 8 from 10
- D (3): This would only work if you subtracted 7 from 10

Why A is correct:
When you start with 3 apples and remove 1, you subtract: 3 − 1 = 2 apples remaining.

Why the others are wrong:
- B (1): This would only be correct if you took away 2 apples, not 1.
- C (3): This ignores that you removed an apple—the amount didn't change.
- D (5): This is more than you started with; you removed an apple rather than added one.

A. 5 ✓

When you subtract 2 from 7, you're taking away 2 items, leaving you with 5. You can count it: 7, 6, 5—that's two steps down.

Why the others are wrong:
- B (6): This is only one step down from 7; you need to subtract 2, not 1.
- C (8): This is adding 1 to 7, not subtracting.
- D (9): This is adding 2 to 7, the opposite operation.

A. 7 is correct because when you subtract 1 from 8, you count back one number: 8 - 1 = 7.

B. 10 is wrong—that's adding 2 to 8, not subtracting 1.

C. 9 is wrong—that's only subtracting 0 or counting up, not back.

D. 5 is wrong—that would be subtracting 3, not 1.

A. 1 ✓

When you start with 2 cookies and give away 1, you subtract: 2 - 1 = 1. You keep 1 cookie.

Why the others are wrong:
- B (2): You'd still have 2 only if you didn't give any away.
- C (0): You gave away only 1 cookie, not both of them.
- D (10): There's no way to gain cookies in this problem; you only gave some away.

A. 0 ✓

When you subtract a number from itself, you always get zero. Here, 5 - 5 means "take away 5 from 5," leaving nothing.

Why the others are wrong:
- B, C, D (1, 2, 3): These would only be correct if you were subtracting smaller numbers (like 5 - 4 = 1), but you're subtracting the same amount, so there's nothing left.

A. 6 is correct. When you subtract 4 from 10, you remove 4 items, leaving 6 remaining.

B. 8 is wrong—that's what you'd get if you added 4 and 4 instead.

C. 9 is wrong—that's only 1 less than 10, not 4 less.

D. 5 is wrong—that would be the answer to 10 - 5 instead.