Okay so first figure out what 2.4 times 10 with the power of negative 3 is.
2.4 times 10 is 24 and 24 to the power of 3 is 13,824
so an addition problem could be 5,986+7,838= 13,824
then you could do for a subtraction problem 23,789- 9,965 = 13,824
I hope this helped you. (;