There are multiple calculator application that can be used in freebsd . You can use the command pkg search calc in order to find calculators .

$ pkg search calc 
# search for an application , which has ,
# in its name the pattern calc      
CalculiX-ccx-2.16_2            Three-Dimensional Structural Finite Element Program
R-cran-epicalc-2.15.1.0_11     Epidemiological calculator
acalc-0.3                      Simple and pretty Qt5-based expression calculator
calc-2.12.7.2_1                Arbitrary precision calculator
calcoo-1.3.18_7                RPN and algebraic scientific calculator
calculix-2.16.1                Three-Dimensional Structural Finite Element Program
calcurse-4.5.1                 Text-based calendar and scheduling application
gnome-calculator-3.28.2_2      GNOME 3 calculator tool
gnu-ipcalc-0.2.3_1             Modern network address calculation tool for IPv4 and IPv6
hexcalc-1.11_3                 Multi-radix calculator for x11
ipcalc-0.41_3                  IP Calculator
ipv6calc-2.2.0                 Convert, change, and calculate with IPv6 addresses
kcalc-20.04.2                  Scientific calculator for KDE
lcalc-1.23_1                   L-function c++ class library and the CLI program lcalc
libticalcs2-1.1.9              TI calculator library
lrcalc-1.2_1                   Littlewood-Richardson Calculator
lumina-calculator-1.6.0        Scientific calculator from the Lumina Desktop
mate-calc-1.24.0               MATE calculator tool based on the old calctool for OpenWindows
mbasecalc-1.1_8                Simple calculator program inspired by basecalc
p5-CAD-Calc-0.27_2             Generic cad-related geometry calculations
p5-Color-Calc-1.074_1          Simple calculations with RGB colors
p5-Date-Calc-6.4               Gregorian calendar date calculations
p5-Date-Calc-Iterator-1.02     Iterate over a range of dates
p5-Date-Calc-XS-6.4            XS wrapper and C library plug-in for Date::Calc
p5-Date-Pcalc-6.1_1            Gregorian calendar date calculations
p5-DateTime-Util-Calc-0.13002_4 DateTime Calculation Utilities
p5-Math-BaseCalc-1.019         Convert numbers between various bases
p5-Math-BigInt-FastCalc-0.5009 Math::BigInt::Calc with some XS for more speed
p5-Math-Calc-Units-1.07_1      Human-readable unit-aware calculator
p5-WWW-Google-Calculator-0.07_1 Simple interface for Google calculator
pantheon-calculator-1.5.5      Simple calculator written in Vala
physcalc-2.4_1                 Flexible calculator that behaves much like units(1)
py27-gcalcli-4.0.4_1           Google Calendar Command Line Interface
py27-ipcalc-1.99.0             Module to perform IP subnet calculations
py37-gcalcli-4.0.4_1           Google Calendar Command Line Interface
py37-ipcalc-1.99.0             Module to perform IP subnet calculations
rofi-calc-1.7                  Do live calculations in rofi
rpcalc-0.8.2_3                 Simple RPN calculator
sipcalc-1.1.6                  IP subnet calculator with IPv6 support
sscalc-1.0                     Sunrise and sunset time calculator
subcalc-1.3                    Advanced IP/IPv6 subnet calculation and discovery
subnetcalc-2.4.15              IPv4/IPv6 Subnet Calculator
transcalc-0.14_12              Analysis and synthesis tool for RF and microwave transmission lines
wcalc-2.5_3                    Natural-expression command-line calculator
wikicalc-1.0                   Open Source Wiki-Spreadsheet
wmCalClock-1.26_1              Another Window Maker calendar/clock dockapp
xcalc-1.1.0                    Scientific calculator for X
xfce4-calculator-plugin-0.7.0_1 Simple calculator for the Xfce panel

acalc

The acalc application can be installed by issuing the command pkg install acalc . It has two views , simple and original which contains more functions .

gnome-calculator

The gnome calculator can be installed by issuing the command pkg install gnome-calculator . it has a basic mode , an advanced mode , a financial mode , a programming mode , and a keyboard mode .

kcalc

This calculator created by kde , can be installed by using the command pkg install kcalc. It has a simple mode , a science mode , a statistic mode and a numeral system mode.

mate-calc

The mate-calc can be installed by using pkg install mate-calc . It has a basic mode , an advanced mode , a financial mode , and a programming mode .