What you need to know

Things to remember:

  • Numbers can be split into smaller ones to make them more manageable.
  • When adding or subtracting by 10, the 10s go up or down by 1.
  • When adding 10 to a number in the 90s, the 100s go up by 1 and the tens become 0.
  • When adding or subtracting 100, the 100s go up or down by 1.
  • When adding 100 to a number in the 900s, we get a 1000 and the hundreds become 0.

We can split up a number into units, 10s, and 100s.

237= 200 + 30 + 7

682=600+80+2

Let’s try using this in a question.

325+100=300+20+5+100=300+100+20+5=400+20+5=425

187-10=100+80+7-10=100+80-10+7=100+70+7=177

Example Questions

Question 1: Add the following numbers

678-100

Answer

Question 1: Add the following numbers

 

678-100

Question 2: Add the following numbers

133+10

Answer

Remember, we can split it up.

 

133+10=100+30+3+10=100+30+10+3=100+40+3=143