(i) (99)3 = (100 – 1)3
= (100) – (1)3 – 3 × 100 × 1(100 – 1)
= 1000000 – 1 – 30000+ 300 = 970299
(ii) (9.9)3 = (10 – 0.1)3
= (10)3 – (0.1)3 – 3 × 10 × 0.1(10 – 0.1)
= 1000 – 0.001 – 3(9.9)
= 1000 – 0.001 – 29.7 = 970.299
(iii) (10.4)3 = (10 + 0.4)3
= (10)3 + (0.4)3 + 3 × 10 × 0.4(10 + 0.4)
= 1000+ 0.064 + 12(10.4)
= 1000 + 0.064 + 124.8 =1124.864
(iv) (598)3 = (600-2)3
= (600)3 – (2)3 – 3 × 600 × 2(600 – 2)
= 216000000 – 8-21,60,000 + 7200
=21,38,47,192
(v) (402)3 = (400 + 2)3
= (400)3 + (2)3 + 3 × 400 × 2(400 + 2)
= 64000000 + 8 + 960000 + 4800
= 64964808
(vi) (1002)3 = (1000 + 2)3
= (1000)3 + (2)3 + 3 × 1000 × 2(1000 + 2)
= 1000000000 + 8+ 6000000 + 12000
= 1006012008
