Mental math refers to performing calculations in your head without using a calculator or writing them down. It involves using your mind to solve math problems quickly and accurately. Full definition
In the meantime, doing mental math with visual training wheels helps build numerical flexibility and agility. (educationworld.com)
Think of this transitional stage as mental math with training wheels. (educationworld.com)
• Perform transactions using cash registers, calculators, and mental math skills; and issue refunds, change due, receipts, and credits promptly to customers. (resume-now.com)