Related Clues:

• Use a calculator
• Do arithmetic
• Put into the mix
• Put in with the rest
• "Not only that ..."
• Say more
• Enlarge, as one's lead
• Put 2 and 2 together
• Lengthen (with "to")
• Ancient pyramid builders
• Coupled with
• Beef up
• Positive sign
• Word found on a dipstick
• Also say