Write the number in standard form.

1.66*10^9

1,660,000,000

Step-by-step explanation:

The exponent of 9 means the mantissa is multiplied by 10^9 = 1,000,000,000.

To put the number in standard form, carry out that multiplication:

1.66*10^9 = 1.66*1,000,000,000 = 1,660,000,000