Multiplying by 99 and 999 (Fast)

Transcript

Multiplying by 99 and 999 (Fast)Let’s say we need to multiply 3874 × 99 Now, to do this, we make 99 = 100 – 1 3874 × 99 = 3874 × (100 – 1) = 387400 – 3874 Putting 387400 and 3874 below each other to subtract Multiplying by 999 Let’s say we need to multiply 3874 × 999 Now, to do this, we make 999 = 1000 – 1 3874 × 99 = 3874 × (1000 – 1) = 3874000 – 3874 Putting 3874000 and 3874 below each other to subtract