Estimate each product using rounding or compatible numbers: 4.05 x 11

Question

Estimate each product using rounding or compatible numbers: 0.83 x 12
Estimate each product using rounding or compatible numbers: 0.89 x 51
Estimate each product using rounding or compatible numbers: 99.3 x 92
Estimate each product using rounding or compatible numbers: 47.2 x 93

Answer 1

4x10=40
and so on