Tens & Ones
Teaching place value with tens and ones forms the foundation of all number work in Year 2, yet many pupils struggle to grasp that the digit 3 in 34 represents 30, not just 3. This concept underpins addition, subtraction, and number sense throughout primary school.
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Why it matters
Understanding tens and ones connects directly to money skills that pupils use daily—recognising that £34 means 3 ten-pound notes plus 4 pound coins. This place value knowledge becomes essential when children tackle two-digit addition problems like 25 + 18, where they must understand that 2 represents 20, not just 2. In real-world contexts, pupils apply this understanding when counting classroom equipment (bundling 10 pencils together), organising sports day teams (groups of 10 children), or calculating bus fares (£1.50 = 1 pound and 5 ten-pence coins). The UK National Curriculum specifically requires Year 2 pupils to recognise place value in two-digit numbers, making this topic crucial for SATs preparation and progression to Key Stage 2 mathematics.
How to solve tens & ones
Place Value — Tens & Ones
- In a two-digit number, the left digit = tens, the right digit = ones.
- 34 = 3 tens + 4 ones = 30 + 4.
- The value of a digit depends on its position.
- Hundreds are to the left of tens: 245 = 2 hundreds + 4 tens + 5 ones.
Example: In 72: the 7 is worth 70 (7 tens), the 2 is worth 2 (2 ones).
Worked examples
You have 80 apples. How many bags of 10 can you fill?
Answer: 8
- Figure out how many groups of 10 fit in 80 → 80 ÷ 10 = 8 — Divide by 10 to find the number of bags: 80 ÷ 10 = 8. Each bag holds exactly 10 apples.
- Check → 8 × 10 = 80 ✓ — 8 bags × 10 apples = 80 apples. All apples are bagged!
What number has 7 tens and 7 ones?
Answer: 77
- Each position has a value → tens place = ×10, ones place = ×1 — In our number system, each spot has a different value. The tens place is worth 10 times more than the ones place. Think of it like: tens are 'big' coins worth 10, and ones are 'small' coins worth 1.
- Multiply the tens: 7 × 10 → 7 × 10 = 70 — 7 tens means 7 groups of 10, which is 70.
- The ones are just themselves → 7 × 1 = 7 — The ones digit is 7. Each one is worth just 1.
- Add them together → 70 + 7 = 77 — Combine the tens and ones: 70 + 7 = 77. The number is 77!
Which digit is in the tens place of 34?
Answer: 3
- Look at the digits of 34 → 34 → 3 and 4 — The number 34 has two digits. In a two-digit number, the LEFT digit is always the tens and the RIGHT digit is always the ones.
- Identify the tens digit → 3 — The tens digit is 3 (the left digit). It's worth 30. The ones digit is 4 (the right digit), worth just 4.
Common mistakes
- Pupils often confuse digit position, writing that 42 has 2 tens and 4 ones instead of 4 tens and 2 ones, mixing up left and right positions.
- When asked for the value of 6 in 63, students frequently answer 6 instead of 60, forgetting that position determines value.
- Children commonly add place values incorrectly, calculating 5 tens + 3 ones as 53 instead of recognising this already equals 53.
- Many pupils struggle with expanded form, writing 84 as 8 + 4 instead of 80 + 4, omitting the tens value entirely.