You only have two sig figs at best for an engineering estimate you could get close by rounding up to 10x15 which is 150.  The error on both terms is gonna round to about ten so subtract both error factors from the 1st order estimate and get about 150-10-10 aka a decent engineering estimate done in the head to two sig figs is 130.  Thats not too far from a calculated answer, only a couple percent off, which is smaller than the measurement error.<p>The most important estimating still, after manipulation of sig figs is knowing which way to bend for the overall system.  So say I&#x27;m tiling a kitchen floor or buying paver bricks for a modest sized patio.  Well, some raw material is going to be too ugly to use and I&#x27;m going to screw up some of the trimming and cutting and I&#x27;m going to drop some, and the cost of the gasoline and time to drive out to the home center and buy one more (mismatched) tile or brick is very high, so in that scenario I&#x27;d buy the 10x15=150 tiles and hope thats enough (I&#x27;m feeling lucky today).  On the other hand if I had 9 steel chains each rated (by whom? Static or dynamic loads?  Point concentrations or perfectly (LOL) distributed?) to 1400 pounds each, I would round way down for safety&#x27;s sake and not suspend more than 10 x 10 or 10000 pounds on that platform.  Even if the chains are rated properly I only need to screw up or fail four of them and the thing crashes down.<p>Anyway for engineering purposes 9x14 is somewhere around 100 to 150.