text: if arranging the s$1 coin to measure the height of wtc towers, how many coins do we need?can singapore afford? assuming the wtc towers still exist. not a trick question. to roof, it's 1,368 ft (417.0 m).  $1 coin thickness = 2.4mm = 2.4 x 10^(-3) m  so we need 417 / 2.4x10^(-3) = 173750 coins  it means $173,750   a family can easily afford it