PSLE
Dylan packed 408 biscuits into large and small boxes. He filled each large box with 16 biscuits and each small box with 8 biscuits. All the boxes were full and no biscuits were left over. What was the least number of boxes used by Dylan?
To have the least number of boxes, Dylan had to use as many as large boxes as possible.

If Dylan used only large boxes,
number of large boxes used
= 408 ÷ 16
= 25 r 8 (x) There should be no remaining biscuits left.

If 25 large boxes are used, there are 8 biscuits left, Dylan had to use less large boxes so that the rest of the biscuits were packed in small boxes.

If Dylan used 24 large boxes,
number of biscuits to be packed in small boxes
= 408 - (24 x 16)
= 408 - 384
= 24

Number of small boxes needed to pack 24 biscuits
= 24 ÷ 8
= 3 (✓) There is no remaining biscuits left.

Least number of boxes that Dylan used
= 24 + 3
= 27

Answer(s): 27