First thing to note is that 3ft=1yd, so let's make things a little simpler by saying the segments are 7 yards and 17 inches long.
19 segments x (7yd + 17in) per segment = 133yd + 323in
now change 323in to feet by dividing by 12in/ft to get 26ft with 11in left over. So we have
133yd + 26ft + 11in
now change the 26ft to yards by dividing by 3ft/yd to get 8yd with 2ft left over. So we have
141yd + 2ft + 11in
Because 19 is very close to 20 you can actually you can make the numbers simple enough to do this one in your head if you also realize that 3ft is a yard and 17 is only one inch short of being half a yard. Now in your head you can multiply 7.5yd by 20 to get 150yd, but that is really 20in too long because each segment was really 1in less than 7½ yards. Also, there were only 19 segments instead of 20, so it is really another 7yd 17in too long, or a total of 7yd and 37in too long, which is 8yd 1in. This means we need to subtract 8yd 1in from 150yd to get the answer, which of course is 1in less than 142yd, which is 141yd 2ft 11in.
So you do not really need a calculator if you can do the following five very easy calculations in your head:
7.5 x 20 = 150
20 + 17 = 37
150 - 8 = 142
142 - 1 = 141
1yd - 1in = 2ft 11in
19 segments x (7yd + 17in) per segment = 133yd + 323in
now change 323in to feet by dividing by 12in/ft to get 26ft with 11in left over. So we have
133yd + 26ft + 11in
now change the 26ft to yards by dividing by 3ft/yd to get 8yd with 2ft left over. So we have
141yd + 2ft + 11in
Because 19 is very close to 20 you can actually you can make the numbers simple enough to do this one in your head if you also realize that 3ft is a yard and 17 is only one inch short of being half a yard. Now in your head you can multiply 7.5yd by 20 to get 150yd, but that is really 20in too long because each segment was really 1in less than 7½ yards. Also, there were only 19 segments instead of 20, so it is really another 7yd 17in too long, or a total of 7yd and 37in too long, which is 8yd 1in. This means we need to subtract 8yd 1in from 150yd to get the answer, which of course is 1in less than 142yd, which is 141yd 2ft 11in.
So you do not really need a calculator if you can do the following five very easy calculations in your head:
7.5 x 20 = 150
20 + 17 = 37
150 - 8 = 142
142 - 1 = 141
1yd - 1in = 2ft 11in
