Column subtraction is also known as vertical calculations.
You two made a film? Wow, impressive. Oh dear, people don鈥檛 seem to be enjoying it do they?
That鈥檚 alright, we can use number columns to figure out how many people are still here.
Number columns allow you to take large numbers and subtract one from another easily.
It does this by breaking the sum down into different place values and then subtracting those numbers away from one another separately.
So 92 tickets were sold and 27 people have left. We start by putting the original number on top.
Righto. Start with the column on the right. In this case, it鈥檚 the ones.
Because two is smaller than seven we need to borrow a ten from the next number along.
So 12 take away seven gives us five.
Now on to the tens.
Eight take away two gives us six.
And there you have it, 65 people still think your film is worth watching. Not bad.
Ah鈥h鈥uess not.
If the numbers are too high or too difficult to subtract in your head, write them down in columns. Separate the numbers into ones, tens, hundreds and thousands. List the numbers in a column and always start with the ones first.
- Estimate first and check afterwards - it's a good idea to estimate a rough answer first. And always check your actual answer.
- Subtraction is the opposite to addition. So subtraction can always be checked by adding. Check that 182 - 37 = 145 by doing the sum: 145 + 37 = 182
- Look out for these words in problems: take away, difference, less than, minus, decrease, fewer than, reduce. They all indicate subtraction.
More on Number and number processes
Find out more by working through a topic
- count9 of 25
- count10 of 25
- count11 of 25
- count12 of 25
