What should come in place of the question mark (?) in the following questions?
$$5\frac{1}{5}+2\frac{3}{5}+1\frac{2}{5}=?$$
13% of 258-?=10
$$\frac{4}{5}\times2\frac{3}{4}\div\frac{5}{8}=?$$
623.15-218.82-321.43=?
$$5437-3153+2284=?\times50$$
What approximate value should come in place of the question mark (?) in the following questions ?
(you are not expected to calculate the exact value)
$$16.003\times27.998-209.010=?$$
$$840.0003\div23.999=?$$
6885.009-419.999-94.989=?
$$(6.5)^{2}=?$$
$$11111\div111\div11=?$$