Step-by-step explanation:
[tex]a) \: 1\% \: of \: 400 = \frac{1}{100} \times 400 = 4 \\ \\ b) \: 1\% \: of \: 2500 = \frac{1}{100} \times 2500 = 25 \\ \\ c) \: 1\% \: of \: 657= \frac{1}{100} \times 657 = 6.57 \\ \\ d) \: 1\% \: of \: 12= \frac{1}{100} \times 12 = 0.12 \\ [/tex]