Year 1 Number Cheatsheet

• We can count forward and backward from 1 to 100
• Place value tells us the value of each digit in a number
• A number has a tens digit and an ones digit (e.g., 23 has 2 tens and 3 ones)
• Skip counting means jumping by a certain number: count by 2s (2, 4, 6...), by 5s (5, 10, 15...), by 10s (10, 20, 30...)
• We can add and subtract within 20 using strategies like counting on, counting back, or using number lines
• Equal sharing means dividing fairly, and halves mean splitting something into 2 equal parts
• We recognize Australian coins and notes: 1c, 5c, 10c, 20c, 50c, $1, $2, $5, $10, $20

Example 1: Understanding place value

What does 37 mean?

Step 1: Look at the tens digit: 3
Step 2: Look at the ones digit: 7
Step 3: 3 tens = 30, and 7 ones = 7
Answer: 37 = 30 + 7 (three tens and seven ones)

Example 2: Skip counting by 5s

Count by 5s up to 50. Say each number.

Step 1: Start at 5
Step 2: Jump by 5 each time: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50
Answer: You've skip counted by 5s!

Example 3: Adding within 20

Work out 14 + 5.

Step 1: Start at the bigger number: 14
Step 2: Count on 5 steps: 15, 16, 17, 18, 19
Answer: 14 + 5 = 19

Example 4: Finding half

What is half of 8 apples?

Step 1: Split 8 into two equal groups
Step 2: Each group has 4 apples
Answer: Half of 8 is 4

• Mistake: Not understanding that the digit position matters in place value. Fix: Remember that 23 is NOT the same as 32 because the tens and ones places are different.
• Mistake: Starting at the wrong number when skip counting. Fix: Always start at the number you're skip counting by (start at 5 for skip counting by 5s).
• Mistake: Counting the starting number twice when adding. Fix: When you count on, don't count the first number again.
• Mistake: Confusing halves with any split. Fix: A half must be two equal parts. If they're not equal, it's not a half.

• Digit: A single symbol used to write numbers (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
• Place value: The value of a digit based on its position
• Tens: Groups of 10
• Ones: Single units
• Skip count: Count by jumping the same number each time
• Addition: Putting groups together (+ means add)
• Subtraction: Taking away (− means subtract)
• Equal: The same
• Half: One of two equal parts
• Coin: Metal money