An overhead, slightly angled close-up depicts a silver-colored Casio fx-991ES PLUS scientific calculator resting on an open, white lined notebook filled with handwritten notes in blue ink

An overhead, slightly angled close-up depicts a silver-colored Casio fx-991ES PLUS scientific calculator resting on an open, white lined notebook filled with handwritten notes in blue ink. The calculator, exhibiting minor wear on its casing, prominently displays its brand and model name, "CASIO fx-991ES PLUS," along with "NATURAL-V.P.A.M." and "TWO WAY POWER." Its dark green display and a small rectangular solar panel are visible. The notebook's pages contain chemical engineering or scientific formulas and text, including phrases like "Higher Conversion per Unit Volume for reactor," "Smaller reactor Volume is needed to achieve Conversion," and mathematical expressions such as "X_A = N_Ao - N_A" and "Y_P = N_A / (N_Ao - N_A)." A dark, out-of-focus object, possibly a pen, partially obscures the calculator's left side. The scene suggests an academic or technical study environment. This image was captured in Jos, Nigeria.