`d) 194^2 + 194.12 + 6^2`
`= 194 . (194 + 12) + 6^2`
` = 194 . 206 + 36`
` = (200 - 6)(200 + 6) + 36`
` = 200^2 - 6^2 + 36`
` = 40000 - 36 + 36`
` = 40000`
`e) 85^2 - 30.85 + 15^2`
` = 85 .(85 - 35) + 225`
` = 85 . 50 + 225`
` = (70 + 15)(70-15) + 225`
` = 70^2 - 15^2 + 225`
` = 4900 - 225 + 225`
` = 4900`