Question

Find the product of the :
Greatest number of four digits and the greatest number of three digits

Answer 1

Greatest number of four digits = 9999
and Greatest number of three digits = 999
Required product = 9999 x 999
= 9999 x (1000 – 1)
= 9999 x 1000 – 9999 x 1 (using distributivity)
=(10000-1) x1000 – (10000-1) x 1
= 10000 x 1000 –1 x 1000 – 10000 + 1
= 10000000 – 1000 – 10000 + 1
= 10000001 – 11000
= 9989001