Welcome to Addition, Subtraction, and Place Value
Today we’ll learn three things: adding numbers, taking away numbers (subtraction), and what place value means (ones, tens).
1) Place Value: What Do Digits Mean?
In a number like 47, each digit has a place:
- 4 is in the tens place — that’s 4 tens = 40.
- 7 is in the ones place — that’s 7 ones = 7.
So, 47 means 4 tens and 7 ones: 40 + 7 = 47.
2) Addition (Putting together)
Adding means combining groups to make more. We start with small numbers we can count in our heads.
- Same-ones: Add ones first. Example: 23 + 5
- Count from 23 by 5: 24, 25, 26, 27, 28 → 28.
- Regroup if needed: If the ones total is bigger than 9, swap 10 ones for 1 ten.
- Example: 17 + 8 → ones: 7 + 8 = 15 → write 5, carry 1 to tens → tens: 1 + 1 = 2 → total 25.
Quick tip: Use fingers, a number line, or blocks to help visualize.
3) Subtraction (Taking away)
Subtracting means finding how many remain when some are taken away.
- Subtract ones first: 23 − 5
- Count backwards from 23 by 5: 22, 21, 20, 19, 18 → 18.
- If you need to borrow: If you have 12 − 7, you can think 12 is 1 ten and 2 ones. Subtract to get 5.
Tip: Use objects or drawings to show taking away.
4) Simple Word Problems to Practice
- Emma has 14 apples. She gives away 6. How many apples does she have left? 14 − 6 = 8.
- There are 3 bags with 7 marbles each. How many marbles total? 3 × 7 = 21 (this introduces counting in groups).
5) Quick Check Ideas
- Count objects as you answer (fingers, blocks, or counters).
- Speak the steps aloud: “I’m adding ones, then carrying a ten.”
- Use a number line: jump forward for addition, backward for subtraction.
With practice, addition, subtraction, and place value will become easier. Have fun exploring numbers!