Nonvolatile memory device includes memory cell region including first metal pad, peripheral circuit region including second metal pad, memory cell array, input current generator, operation cell array and analog-to-digital converter. Peripheral circuit region is vertically connected by first and second metal pads. Memory cell array in memory cell region includes NAND strings storing multiplicand data, wherein first ends of NAND strings are connected to bitlines and second ends of NAND strings output multiplication bits corresponding to bitwise multiplication of multiplicand data stored in NAND strings and multiplier data loaded on bitlines. Input current generator generates input currents. Operation cell array in memory cell region includes switching transistors. Gate electrodes of switching transistors are connected to second ends of NAND strings. Switching transistors selectively sum input currents based on multiplication bits to provide output currents. Analog-to-digital converter converts output currents to digital values.