← Home

Mental addition and subtraction (age 6+)

PROCEDURAL
Mathematics›Addition & Subtraction|Ages 6—7|ID: mt_AKAtWEwpcj

Add and subtract a two-digit number and ones mentally and using concrete/pictorial representations

Mastery Evidence

  • Calculate 36 + 7 = 43 using objects or mentally
  • Calculate 52 − 4 = 48 using a number line or mentally
  • Explain bridging through 10 when adding ones to a two-digit number

Assessment Prompt

“Can [child] work out '36 + 7' or '42 − 5' in their head — keeping the tens in place and only adjusting the ones?”

Curriculum Standards1 alignment

Maths/Y2/AS/4The national curriculum in England
Add and subtract two-digit numbers and ones

Add and subtract numbers using concrete objects, pictorial representations, and mentally, including a two-digit number and ones.

Mathematics · Key Stage 1

Prerequisites2

Show full prerequisite tree
  • Adding and subtracting hard

    Adding ones to a two-digit number extends Y1 adding within 20

  • The two digits of a two-digit number hard

    Adding ones to two-digit numbers requires understanding tens and ones

    • A Ten Is Ten Ones hard

      Understanding tens and ones place value requires the concept of 10 as a bundle

      • The teen numbers hard

        Understanding 10 as a bundle builds on understanding teen numbers as 'a ten and some ones'

        • How Many in Total? hard

          Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

          • One-to-one counting hard

            Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

        • Reading and writing numbers to 20 hard

          Composing/decomposing teen numbers requires reading and writing those numerals

          • How Many in Total? hard

            Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

            • One-to-one counting hard

              Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

          • Writing digits 0-9 hard

            Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

    • The teen numbers hard

      General two-digit place value extends from understanding teen number composition

      • How Many in Total? hard

        Understanding tens-and-ones composition requires cardinality — knowing numbers represent quantities

        • One-to-one counting hard

          Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

      • Reading and writing numbers to 20 hard

        Composing/decomposing teen numbers requires reading and writing those numerals

        • How Many in Total? hard

          Reading/writing numerals 0–20 requires understanding that numerals represent quantities (cardinality)

          • One-to-one counting hard

            Cardinality principle builds on one-to-one correspondence — you must count correctly to know the last number tells 'how many'

        • Writing digits 0-9 hard

          Writing numerals requires the motor skill of forming digits 0-9 (taught in English handwriting)

Unlocks1