Subtracting multiples of 10

PROCEDURAL

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

Subtract multiples of 10 (10–90) from multiples of 10 using place value strategies

Mastery Evidence

Calculate 70 − 30 = 40
Use base-ten blocks to show 80 − 50 = 30
Explain that subtracting tens is like subtracting the tens digits

Assessment Prompt

“Can [child] quickly work out '80 − 50' or '70 − 40' in their head by thinking about how many tens are left?”

Curriculum Standards1 alignment

1.NBT.6Common Core State Standards for Mathematics

Subtract multiples of 10

Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.

NBT

Prerequisites2

The multiples of 10
hardAges 6—7
Subtraction as taking away or separating
hardAges 4—6

Show full prerequisite tree

The multiples of 10 hard
Subtracting multiples of 10 requires understanding decade numbers as tens
- Counting in 2s soft
  Skip counting in tens supports recognising decade numbers
  - Rote counting to 100 hard
    Skip counting in 2s, 5s, 10s requires fluent rote counting by ones first
    - One-to-one counting hard
      One-to-one correspondence requires knowing the number name sequence
- A Ten Is Ten Ones hard
  Understanding decade numbers as 'some tens and 0 ones' requires the concept of a ten
  - 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)
        
        Sitting and holding a pencil soft
        Same motor skills for digit formation
Subtraction as taking away or separating hard
Subtracting multiples of 10 requires understanding subtraction
- How Many in Total? hard
  Understanding subtraction as taking away requires knowing numbers 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'

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