Three Quick Reps

Room diagonal: a 12 × 16-foot room measures √(144 + 256) = 20 feet corner to corner — handy for running carpet or cable.

Laptop fit: a screen 15 inches wide and 8 inches tall has a √(225 + 64) = 17-inch diagonal, just inside a 17.3-inch bag.

TV check: a 60 × 34-inch panel comes to √4756 ≈ 69 inches.

A few reps and the formula stops being a test answer and becomes a tool you reach for.