DUAL POWERSolar (works only when it is bright) and Battery (one AA battery NOT included). Automatically Power off, save more energy. Note: Please insert one AA battery for continuous and accurate usage 12 DIGITS CALCULATOR12 digits make the calculator most useful for large calculations. Suitable for businessman, worker, teacher, student or anybody that needs make any sort of calculation from time to time BIG BUTTON DESIGNLarge non-stick plastic button, new material, more durable. The calculators adopt scientific big button design in line with the use of human habits and comfortable for touch LARGE DISPLAYLarge eye-angled, upright display, easy to read, easy to carry GREAT VALUE OF 2 PACK2 different functional calculators, 1 basic calculator, 1 updated calculator with root button [M+] Adds the number shown on the display to the number stored in the memory. Example:3*8 + 2*6.If you directly inputs these numbers to the calculator,you will see the wrong answer: 156.If you press [3*8], [M+], [2*6], [M+], then press [MRC] once, you will get the right answer: 36. [M-] Subtracts the number shown on the display to the number stored in the memory. [MRC] Combination of [MR] and [MC]. [MR]: Recall the current memory register value. [MC]: Clear the memory register (set to zero). When you press the key once, the [MR] key was activated, when you press the key twice, the [MC] was activated. [GT] Whenever the [=] key has been pressed, the result will be stored into the Grand Total Memory Example: If you want to calculate [2*3+3*5+6*8],press [2*3=], then [3*5=], then [6*8=]. Then press [GT], you will get the right answer 69 [MU] Stands for Mark Up, which is for calculating GROSS PROFIT MARGIN (GPM). Example: Enter [100] then press the [], then [15] then [MU] key, you will see 117.65 (15% of this total equates to 17.65) [CORRECT] It helps you correct wrong number. If you want to press 458, but you pressed 459, you can then press [CORRECT] key to delete 9 and press [8] key again to correct it [AUTO REPLAY] It helps replay your operation you just pressed You pressed [4x5=] and you will see 20, then you press the [AUTO REPLAY] and you will see 5x, 3, 15 in the calculator screen [CHECK] It helps replay your operation step by step.You pressed [4x5=] and you will see 20, then you press the [CHECK] 3 times, you will see 4x,5,20 separately