The product of which expression contains four decimal places?
5.3478 times 6.4214
6.4 times 9.1
521 times 3.82
14.2 times 0.784

14.2 times 0.784

Step-by-step explanation:

When you check the numbers of digit after the decimal point; you get the idea.

For example; one digit is after the decimal point in 14.2

Three are after the decimal in 0.784;

Adding both 1 and 3 we get 4.

This smart observation when done for the other multiplied numbers do not give us 4.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.