Solar And Battery Calculators For Middle School And College Students Are Product Details ?240 Functions Scientific Calculator?It is a professional scientific calculator that can be counted using stat-data editor calculations. The scientific calculator can also perform basic mathematical operations, including triangular functions, roots, n-th roots, percentages, scores, complex numbers, permutations, linear regression, standard deviations, and variable solving. ?Brightness Adjustment Function?The scientific calculator allows you to adjust the brightness of the screen for optimal display with a simple operation, dimming it to relieve eye fatigue and brightening it for clearer results. ?2-Line Scientific Calculator?Input expressions and arithmetic operations is more easy to read than traditional calculators. The 2 line display shows both input and calculation results, convenient for students to check the calculation process and results. ?Dual Power Source Electronic Calculator?Solar and battery, double safe uninterruptible power, environmental protection and energy saving advantages. ?Ultra-light Portable?Weight: 4.97oz. (141g); Size: 164 x 80 x 17(mm)/6.4 x 3.15 x 0.67(inch); Material: ABS plastic. With slide-on hard case, convenient to carry it outside and hold it on one hand. Payment We accept PayPal and credit cards via PayPal. Taxes - US We collect sales tax, as required by law. Shipping We make every effort of shipping within 3 business day of payment clearing. The estimated delivery time is 2 - 5 business days from the shipping date. Policies If you do need to return your item, please contact us via email (you will receive an email when your product ships with additional details - Subject: Important information about your purchase). You will then be provided with a return shipping label and packing slip. Pack the item carefully. Include the packing slip, apply the shipping label, and return the item within 30 business days of the date you request a return, or your return will be canceled. Once we receive your order we will inspect the return. Please allow up to 5 business days of receiving the returned item for your refund.