12
Remember that in decimal division, the decimal point moves the same way in both numerator and denominator. 0.003 ÷ 0.00025 = 0.03 ÷ 0.0025 = 0.3 ÷ 0.025 = 3 ÷ 0.25. Notice that 0.25 = 1/4 is the reciprocal of 4, so dividing by this is the same as multiplying by 4. Thus, 0.003 ÷ 0.00025 = 3 ÷ 0.25 = 3 × 4 = 12.