10BII Calc HD vs DOC%ZINS Usage & Stats

10BII Calc HD is a business calculator featuring over 100 built-in functions for business, finance, mathematics and statistics. Easily calculate loan payments, interest rates, amortization, discounted cash-flow analyses, TVM (loans, savings, and leasing), bonds and depreciation using a simplified algebraic entry system. The keyboard and display have been carefully optimized for the iPhone, iPod Touch and iPad. Two keyboard layouts and multiple specialized worksheets allow you to do much more than a 10BII calculator while maintaining compatibility with the standard.
 HD version includes: • 2 for the price of 1! iPad and iPhone versions included- use on both your iPad and iPhone • HD graphics included for iPad and iPhone retina displays • iPad version includes full support for slide over and split views. • New worksheets including interactive graphs. 
Features:
 •Time Value of Money- Loans, savings, leases and amortization schedules using both the standard keyboard and a specialized TVM solver window that displays the contents of all the variables for rapid "what if" solutions to your problems. View and mail amortization tables. •Interest Conversion- Nominal and effective rates. •Cash Flows- Net present value, internal rate of return, net future value and net uniform series calculations. Up to 80 cash flows are easily edited and reviewed using the dedicated cash flow editor screen. Entries are added, deleted and modified in a scrolling display with a touch interface unique to the iPhone. •Business Percentages- Percent change, markup, and margin calculations. •Statistics- Mean, standard deviation, correlation coefficient, and linear regression forecasting, weighted mean. Sample editor and plotter, forecasting using linear, log, exp or power fit. •Conversions- 47 world currency rates and over 100 commonly used metric, english and other conversion factors used in financial, business, scientific and engineering calculations. •Scientific- sin, cos, tan, asin, acos, atan plus the hyperbolic trig functions, conversion between rectangular and polar coordinates, conversion between degrees and radians, time functions including h.ms+ and h.ms-, log, ln, 10^x, e^x, y^x, x root of y, fraction part and integer part. Trig functions can be computed in radians, degrees or gradians. •Worksheets- Auto Purchase Black-Scholes Bond BreakEven Cash Flow Analysis Currency Date Depreciation Interest Conversion Lease Loan Amortization Margin & Markup Refinance Statistics Tip TVM Many of the worksheets include interactive graphs. •Audit tape records all calculations. Tape can be mailed, texted or printed. Discover how to use any function on the keyboard by touching the ? key then the key you want to learn about. Help screens are available for all worksheets. 
Quote from a customer:

"Last week I had a meeting with my accountants and my bankers. We were working on the pro forma balance sheets and cash flows for a new project I'm working on.

They were all asking why I had switched to the iPhone for I used to be a die hard "brandX phone" fan. I said that one could do so much more. They said "yea...sure" (they were all using "brandX phones") until I started using your calculator. We were analyzing different payment and amortization schedules. They were so impressed by how easily we could figure out the amount of interest, principal and remaining loan balance for any certain period or combination of periods that in the end they were saying "I have to get me one of those".

 Great product. Thanks."