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

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

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

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

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

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

Answer(s): 27