300
First, cancel the 7s, then the 4s. 0.084 ÷ 0.00028 = 0.012 ÷ 0.00004 = 0.003 ÷ 0.00001. Now, remember that in decimal division, the decimal point moves the same way in both numerator and denominator. 0.003 ÷ 0.00001 = 0.03 ÷ 0.0001 = 0.3 ÷ 0.001 = 3 ÷ 0.01 = 300 ÷ 1 = 300.