Number – addition and subtraction
Adding within 100
Add two two-digit numbers.
Adding two big numbers is easier if you do not try to do it all at once. Split each number into its tens and its ones, add those separately, then put the two answers back together.
Have a play
Walk along the line and watch the tens go past. Every number with a label under it is ten more than the one before.
Tap anywhere on the line.
Worked example
What is 23 + 14?
Split them up. 23 is 20 and 3. 14 is 10 and 4.
Every two-digit number is just some tens and some ones.
Try it together
Your turn: 46 + 18
1.First the tens. What is 40 + 10?
Watch out
When the ones add up to more than ten, do not lose the extra ten. In that last example 6 + 8 came to 14, which is one whole ten and four ones.
Have a go
Have a go on your own: 35 + 27
Hint: 30 + 20 first, then 5 + 7.
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.