hi

this will cover selections from 1 to 20, copy and paste the formula in to the text box of the write to action log, it is a bit long but i cannot see any other way,because you cannot divide a number or zero by 0, but you can devide zero by a number without an error

100/s_1_back_price+IF(runner_number>1,100,0)/IF(runner_number>1,s_2_back_price,1)+IF(runner_number>2,100,0)/IF(runner_number>2,s_3_back_price,1)+IF(runner_number>3,100,0)/IF(runner_number>3,s_4_back_price,1)+IF(runner_number>4,100,0)/IF(runner_number>4,s_5_back_price,1)+IF(runner_number>5,100,0)/IF(runner_number>5,s_6_back_price,1)+IF(runner_number>6,100,0)/IF(runner_number>6,s_7_back_price,1)+IF(runner_number>7,100,0)/IF(runner_number>7,s_8_back_price,1)+IF(runner_number>8,100,0)/IF(runner_number>8,s_9_back_price,1)+IF(runner_number>9,100,0)/IF(runner_number>9,s_10_back_price,1)+IF(runner_number>10,100,0)/IF(runner_number>10,s_11_back_price,1)+IF(runner_number>11,100,0)/IF(runner_number>11,s_12_back_price,1)+IF(runner_number>12,100,0)/IF(runner_number>12,s_13_back_price,1)+IF(runner_number>13,100,0)/IF(runner_number>13,s_14_back_price,1)+IF(runner_number>14,100,0)/IF(runner_number>14,s_15_back_price,1)+IF(runner_number>15,100,0)/IF(runner_number>15,s_16_back_price,1)+IF(runner_number>16,100,0)/IF(runner_number>16,s_17_back_price,1)+IF(runner_number>17,100,0)/IF(runner_number>17,s_18_back_price,1)+IF(runner_number>18,100,0)/IF(runner_number>18,s_19_back_price,1)+IF(runner_number>19,100,0)/IF(runner_number>19,s_20_back_price,1)

mcbee