log725=25log7=25×0.845 =21.125 Its characterlstic is 21⇒ No. of digits =22 log823=log269=69log2 =69×0.301=20.769 Its characterishe is 20⇒ No. of digits =21 log920=log340 =40×log3 =40×0.477=19.08⇒ No. of digts =20 Near about is 22,21,20