(a)
Find the sum of 3985 and 1273.
Notice that the word sum is used but this means add
Quickly estimate the answer
4000 + 1000 = 5000
STEP 1
Write the numbers in two rows and columns aligned
STEP 2
Start with the ones (units) column, writing the answer below the line but in the same column
STEP 3
Move on to the tens (next on the left) column
The sum is 15 so the 5 (ones) is written below the line and the 1 (tens) 'carries over' to the next (hundreds) column
Next is the hundreds column which again results in a two-digit answer
Finally add the digits in the thousands column
Check the final answer is similar to your estimate; 5000 and 5258 are reasonably close
3985 + 1273 = 5258
(b)
Find the difference between 506 and 28.
Notice that the word difference is used; this means subtract
Quickly estimate the answer
500 - 30 = 470
STEP 1
Write the numbers in two rows, column aligned, ensuring the top number is the number being subtracted from
STEP 2
In the ones (units) column, 6 is smaller than 8, so borrow from the next column (tens)
The tens column is 0, so borrow from the column to the left of that (hundreds)
This turns the 0 (in the tens column) into a 10 which we can then borrow from (for the ones column)
16 - 8 can be now be calculated in the ones column
STEP 3
Move onto the tens column which is 9 - 2 = 7
There is nothing to subtract in the last (hundreds) column (4 - 0 = 4)
Check the final answer is similar to the estimate; 470 and 478 are reasonably close
506 - 28 = 478
(c)
Johnny has £32.50 and spends £1.74. Calculate how much money Johnny has left.
This is a subtraction question as Johnny has spent money
Quick estimate
33 - 2 = 31
STEP 1
Align the digits by place value, ensuring £32.50 is the top number and using the decimal points as a starting point
Using place value holding zeros is optional
STEP 2
The column furthest right is the hundredths column
0 is smaller than 4 so borrow from the next (tenths) column
STEP 3
Next is the tenths column, but again 4 is smaller than 7 so borrow 10 from the ones column
14 - 7 = 7 in the tenths column and continue working 'right to left'
Check the final answer is similar to the estimate; £31 and £30.76 are reasonably close
Johnny has £30.76 left