how do you add two numbers with the same exponent and also with different exponents?

Question

This is the math problem: 6.4x10^6 meters + 1.7x10^6 meters + 3.8x10^5km

Answer 1

The problem involves different units and thus to work it out you need to convert everything to the same units. either km to m or m to km. I recommend km to m.
This would then be 3.8x10^5km * 1000m/1km= 3.8x10^8m

Now when multiplying everything together just add the exponents and multiply the coeficients.
Like this;
6.4x1.7x3.8 and 10^(6+6+8)
thus you get
41.344x10^20 or 4.1344x10^21

Answer 2

3.8 * 10^5 Km = 3.8 * 10^5 * 1000 meters =
= 3.8 * 10^5 * 10^3 meters = 3.8 * 10^8 meters

6.4 * 10^6 = 0.064 * 10^8

1.7 * 10^6 = 0.017 * 10^8

6.4x10^6 meters + 1.7x10^6 meters +
+ 3.8x10^5km = 0.064 * 10^8 meters +
+ 0.017 * 10^8 meters + 3.8 * 10^8 meters =
= 0.081*10^8 meters + 3.8 * 10^8 meters =
= 3.881 * 10^8 meters = 3.881 * 10^5 Km

Answer 3

Normally you can't just add exponents together. But if you think of these numbers as being multiples of 10^6, you can simplify them. Watch your units!

(6.4 x 10^6 m) + (1.7 x 10^6 m) + (3.8 x 10^5 km)
(6.4 x 10^6 m) + (1.7 x 10^6 m) + (3.8 x 10^8 m)
(6.4 x 10^6 m) + (1.7 x 10^6 m) + (380 x 10^6 m)
(6.4 + 1.7 + 380) *10^6 m
Add up the side part to simplify.

Answer 4

64X10^5m+17X10^5+38X10^7=1088X10^5+38X10^7