How do you evaluate $6.4\times 9.9$ ?

Question

1925 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-02-24T19:13:15

$6.4xx9.9 = 63.36$

$6.4xx9.9 = 6.4xx(10-0.1)$

$color(white)(6.4xx9.9) = (6.4xx10)-(6.4xx0.1)$

$color(white)(6.4xx9.9) = 64-0.64$

$color(white)(6.4xx9.9) = 63.36$

How do you evaluate 6.4\times 9.96.4\times 9.9?