JAMB 1995 · UME · Q1

Calculate $3310_5 - 1442_5$ .

Worked solution (try it first)

Change to base ten: $3310_5 = 375 + 75 + 5 = 455$ and $1442_5 = 125 + 100 + 20 + 2 = 247$ .
Subtract: $455 - 247 = 208$ .
Change back: $208 = 1 \times 125 + 3 \times 25 + 1 \times 5 + 3$ , so the answer is $1313_5$ , option A.