Best Sharp Calculators for Sum

i bought a sharp el-506r eight years ago because i thought it was the best deal under $20 for a scientific calculator.

the sharp el-w516b was a replacement for my ti-68 that i had for years before it quit.

i just purchased the sharp el-w506 scientific calculator from the uk at a great low price (from oxford educational).

in my youth i had a previous version of this calculator, the sharp el-506d, which had scads of functions i did not understand the purpose of, but was fascinated with nonetheless.