Answer:
4.03 × 10⁷
Explanation:
Estimate the product the given number.
(19)(2,120,400)
Product : 19×2120400
Product: 40287600
now write in scientific notation.
Scientific notation:

where, k is between 0 to 9 and n any integers.
If decimal move from right to left then exponent positive.
40287600 = 4.03 × 10⁷
Estimate product of given number in scientific notation is 4.03 × 10⁷