The pieces are 1, 6 and 8 units, 15 units in all. The longest piece (8 units) is 48 cm.

Pipe1u6u8u = 48 cm

Plain numbers are given; italic underlined numbers are worked out.

  1. Longest → 8 units = 48 cm
  2. 1 unit → 48 ÷ 8 = 6 cm
  3. Whole pipe → 15 units = 15 × 6 = 90 cm

The pipe was 90 cm long before it was cut.

Check: 6 + 36 + 48 = 90 cm. ✓