0.006 x 100 = 0.6
0.006 times 100 is 0.6. Multiplying by 100 shifts the decimal point two places to the right, which is also the step that turns a decimal into a percentage: 0.006 is 0.6 percent.
0.006 × 100 = 0.6
Move the point, do not add zeros
0.006 is six thousandths. Slide the decimal point two places to the right and it becomes 0.6, six tenths. One hop per zero in the 100, every time. Adding zeros to the end of 0.006 does nothing at all, since 0.00600 is the same value as 0.006.
The two wrong answers
0.06 comes from moving the point one place instead of two. 6 comes from moving it three. A quick sanity check settles which is right: 0.006 is smaller than 0.01, and 0.01 x 100 is exactly 1, so the answer has to be less than 1. That rules out 6 immediately.
Reading it as a percentage
Decimals become percentages by multiplying by 100, so the decimal 0.006 is 0.6 percent. In markets that same quantity is quoted as 60 basis points, since one basis point is 0.01 percent.
The same move on other decimals
Three places instead of two: 0.07 x 1000 = 70.