a) 20042 - 16
= 20042 - 42
= (2004 - 4)(2004 + 4)
= 2000.2008
= 4016000
b) 8922 + 892.216 + 1082
= 8922 + 2.892.108 + 1082
= (892 + 108)2
= 10002
= 1000000
c) 10,2.9,8 - 9,8.0,2 + 10,2.0,2
= 9,8(10,2 - 0,2) + 2,04
= 9,8.10 + 2,04
= 98 + 2,04
= 100,04
d) 362 + 262 - 52.36
= 362 - 2.36.26 + 262
= (36 - 26)2
= 102
= 100