Column addition and subtraction
The Maths Habit
Sam works out 247 + 186 and gets 31 213.
How can you tell straight away that Sam is wrong?
Both are under 300, so the answer is under 600. It is 433.
A cinema has 742 seats. 386 seats are taken. How many seats are free?
A school has 467 boys and 485 girls. How many students are there altogether?
952
Find the missing digits: 3□6 + 24□ = 591
346 + 245
Find the missing number: 605 − □ = 238
605 − 238 = 367